JP3152969B2 - Single crystal sapphire bonded body and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal sapphire bonded body and a method for producing the same.

[0002]

2. Description of the Related Art Single crystal sapphire joints are
As proposed in JP-A-59-233000, etc., the single-crystal sapphire bodies that have been mirror-finished from the past have been brought into close contact with each other,
In a vacuum (10 ^-5 to 10 ^-6 Torr) while applying a slight pressing force
Thus, the joined body was manufactured by heating at a high temperature of 1000 to 1500 ° C. or more.

[0003]

A high vacuum and a high temperature are required to join single crystal sapphire bodies together, and a little pressing force is required. Further, it is difficult to join the end faces of the rod-shaped body, and the shape that can be joined is limited to a planar shape.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and has made it possible to join single crystal sapphire bodies at a relatively low temperature without requiring a special atmosphere under atmospheric pressure. In order to achieve this, a single crystal sapphire joined body is formed by bringing the joining surfaces of a single crystal sapphire body in which a silicon film is adhered to a mirror-finished joining surface into close contact with each other and joining them together.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on specific embodiments shown in the drawings. As shown in FIG. 1, each of the bonding surfaces 3 and 4 of the single-crystal sapphire body 1 and the single-crystal sapphire body 2 to be bonded has a center average roughness (Ra).
Mirror finish to 0.05 μm or less, preferably 0.03 μm or less.

First, the crystal orientation of single crystal sapphire will be described. Single crystal sapphire is hexagonal, and according to the plane orientation shown in FIG. 2, a (0001) plane (generally called a C plane) exists in a direction perpendicular to the C axis of the crystal. There are a ₁ axis, a ₂ axis and a ₃ axis in the direction of rotation and the rotational symmetry direction so as to have a central angle of 120 °, and the three planes perpendicular to these three axes are crystallographically equivalent. Yes, and that surface is the (11 bar 20) surface (generally called the A surface). In addition, the plane perpendicular to the R axis inclined 57.6 ° in the m axis direction (the m axis direction is an axis perpendicular to the side surface of the hexagonal prism) with respect to the C axis is the (1 bar 102) plane (generally the R plane). Call).

[0007] The bonding surfaces 3 and 4 are optimally the same surfaces such as A surfaces or R surfaces. This is because the silicon single crystal film described later has the highest density difference on the R-plane. Here, the R surface is (1 bar 102)
Refers to a plane of ± 2 °. The single crystal sapphire bodies 1 and 2 can be easily formed with necessary surfaces by manufacturing them by the EFG method.

Next, as shown in FIG. 3, silicon single crystal films 5 and 6 are applied to the bonding surfaces 3 and 4 of the single crystal sapphire bodies 1 and 2 by thermal CVD at a thickness of 0.1 to 1.0 μm. . At this time, since the bonding surfaces 3 and 4 are mirror-finished, the surfaces of the silicon single crystal films 5 and 6 also have mirror surfaces. Thereafter, the single-crystal sapphire body 1 is subjected to a hydrophilization treatment by immersing each of the single-crystal films 5 and 6 in a mixed solution of sulfuric acid and hydrogen peroxide, and no foreign matter is present between the joints, as shown in FIG. The silicon single crystal film 5 and the silicon single crystal film 6 of the single crystal sapphire body 2 are opposed to each other and adhered to each other for bonding.

Further, the joint is heated to 300 ° or more to increase the joint strength. As a heating method, a high-temperature furnace may be used, or a lamp annealing method may be used, utilizing the property of sapphire transmitting light and absorbing silicon. Such bonding strength of the bonded body obtained is usually 10-20 kg / cm ² or so, depending on the conditions of the heat treatment can also be a 100 to 200 kg / cm ^2.

As an application example of the single crystal sapphire bonded body, there is a formation of a diaphragm for a pressure sensor. First, as shown in FIG. 5, the bonding surface of the single crystal sapphire body 11
12 is matched with the R surface, and the R surface is mirror-finished. Next, as shown in FIG. 6, the bonding surface of the single crystal sapphire body 11
A silicon single crystal film 13 is deposited on 12 by a thermal CVD method or the like.

On the other hand, as shown in FIG. 7, the bonding surface 16 of the single crystal sapphire body 15 having a through hole 14 formed in the center of the other is made to match the R surface, and the R surface is mirror-finished. Further, as shown in FIG. 8, a silicon single crystal film 17 is deposited on the bonding surface 16 of the single crystal sapphire body 15 by a thermal CVD method or the like. Finally, as shown in FIG.
The silicon single crystal film 13 of FIG. 1 and the silicon single crystal film 17 of the single crystal sapphire body 15 are opposed to each other and bonded to each other.

The above-prepared single-crystal sapphire body 11 on the upper surface of the diaphragm is mirror-finished, and further heat
After a silicon film is deposited by the VD method, a silicon film is processed to form a resistor bridge circuit that senses pressure, and a sensor that detects pressure from the through hole 14 of the lower single crystal sapphire body 15 may be used. it can.

[0013]

As described above, the present invention relates to a single-crystal sapphire joined body in which the joining surfaces of a single-crystal sapphire body in which a silicon film is adhered to a mirror-finished joining surface are brought into close contact with each other and joined. Because of this, it is possible to join single crystal sapphire bodies at a relatively low temperature (300 ° C or higher, preferably 900 to 1000 ° C or higher), at atmospheric pressure, without requiring a special atmosphere, and with a small manufacturing apparatus. Yes.

Further, the present invention can easily produce a joined body of a single-crystal sapphire body, so that its application range is wide.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of mirror-finished single crystals to be joined.

FIG. 2 is a three-dimensional diagram illustrating an R-plane of single crystal sapphire.

FIG. 3 is a longitudinal sectional view showing a state in which a silicon single crystal film is applied to a bonding surface of single crystal sapphire to be bonded.

FIG. 4 is a longitudinal sectional view in which single-crystal sapphire having a silicon single-crystal film adhered thereto is bonded with the silicon single crystals facing each other and in close contact with each other.

FIG. 5 is a view for explaining the formation of the diaphragm, and is a longitudinal sectional view showing a state where the R-plane of the bonding surface of the single crystal sapphire is mirror-finished.

FIG. 6 is a longitudinal sectional view showing a state in which a silicon single crystal film is applied to a bonding surface of a single crystal sapphire body.

FIG. 7 is a longitudinal sectional view showing a state where the R-plane of the bonding surface of the single-crystal sapphire body having a through hole formed in the other center is mirror-finished.

FIG. 8 is a longitudinal sectional view showing a state in which a silicon single crystal film is applied to a bonding surface of a single crystal sapphire body.

FIG. 9 is a longitudinal sectional view showing a state in which a single crystal silicon single crystal film and another single crystal sapphire silicon single crystal film are opposed to each other and bonded to each other in close contact to form a diaphragm.

[Description of Signs] 1, 2, 11, 15: Single-crystal sapphire body 3, 4, 12, 16: Junction surface 5, 6, 13, 17: Silicon single-crystal film

────────────────────────────────────────────────── ─── Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C30B 1/00-35/00 CA (STN) WPI (DIALOG)

Claims (2)

(57) [Claims] 1. A bonding surface of a single-crystal sapphire body in which a silicon film is applied to a mirror-finished bonding surface is brought into close contact with each other,
A single crystal sapphire bonded body formed by bonding. 2. A single-crystal sapphire body having a mirror-finished bonding surface, a silicon film deposited on the bonding surface, and a bonding process in which the bonding surfaces are brought into close contact with each other and heated to 300 ° C. or more for bonding. A method for producing a bonded body of crystalline sapphire.